Ariana Grande, an anodyne teen favorite hit by tragedy

It is not immediately clear if the unidentified man acted alone, but the person apparently died in the explosion.

"We have been treating this as a terrorist incident and we believe, at this stage, the attack last night was conducted by one man".

British Prime Minister Theresa May is due to chair a meeting of the government's COBRA emergency committee later Tuesday.

Police responded to reports of an explosion shortly after 10:35 pm (2135 GMT) at the arena, which has a capacity for 21,000 people, and where the USA singer had been performing to an audience that included many children.

She said: "We now know that a single terrorist detonated his improvised explosive device near one of the exits of the venue, deliberately choosing the time and place to cause maximum carnage and to kill and injure indiscriminately".

Both she and Labour Party Leader Jeremy Corbyn have cancelled campaigning for the June general election.

If confirmed by investigators as a "terror" incident, it would be the deadliest in Britain since the 7/7 London bombings - on July 7, 2005, three bombs killed 52 people and injured more than 700 in the city's transit system.

Manchester Police have confirmed that a bomb has exploded at Manchester Arena, killing 22 people and injuring 59.

The US Department of Homeland Security said it was "closely monitoring" the situation. Teenage screams filled the arena just after the explosion Monday night, which also killed the attacker and injured dozens.

"On behalf of the government of Japan and the Japanese people, I would like to express my heartfelt condolences to the victims and extend our sympathies to those who have been injured", he added, reported The Guardian.

"Many of you won't have ever been to Manchester, but you will definitely have heard of it. I don't have words", wrote the 23-year-old, who is popular with teens and pre-teens.

As people were leaving a concert by American pop singer Ariana Grande at the Manchester Arena, loud explosions were heard outside the main area.

The service could also be used by people trying to get to local hospitals to look for loved ones.

"The thing with euro/dollar is that you have quite a positive mood on the euro at the moment", said ABN Amro foreign exchange strategist Georgette Boele.

Train service was suspended at Manchester's Victoria Station, which is next door to the stadium, and all transport lines were reportedly cut off by the authorities after the incident.

The 23-year-old former child star called her last album "Dangerous Woman" but her controversies have been markedly low-key, with the "danger" in her lyrics more about love than anything more sinister.

Grande said she had been left "broken" by the events. "Our thoughts and prayers go out to all of those affected by this terrible tragedy". We will focus on reports from police officials and other authorities, credible news outlets and reporters who are at the scene.

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